Plasma-damage-resistant interconnect structure and methods for forming the same

Abstract

A device structure may include an interconnect-level dielectric material layer located over a substrate, a first metal interconnect structure embedded in the interconnect-level dielectric material layer and including a first metallic barrier liner and a first metallic fill material portion, and an overlying dielectric material layer. An opening in the overlying dielectric material layer may be formed entirely within an area of the first metallic barrier layer and outside the area of the first metallic fill material portion to reduce plasma damage. A second metal interconnect structure contacting a top surface of the first metallic barrier liner may be formed in the opening. An entirety of a top surface the first metallic fill material portion contacts a bottom surface of the overlying dielectric material layer.

What is claimed is: 
     
       1. A method of forming a device structure, comprising:
 forming underlying interconnect-level dielectric material layers embedding underlying metal interconnect structures over a substrate; 
 forming an interconnect-level dielectric material layer over the underlying interconnect-level dielectric material layers; 
 forming a stepped cavity through the interconnect-level dielectric material layer, wherein the stepped cavity comprises a deep cavity vertically extending from a first horizontal plane including a bottom surface of the interconnect-level dielectric material layer to a second horizontal plane including a top surface of the interconnect-level dielectric material layer and a shallow cavity vertically extending from a third horizontal plane located between the first horizontal plane and the second horizontal plane to the second horizontal plane; 
 depositing a first metallic barrier liner layer in the stepped cavity, wherein the first metallic barrier liner layer fills an entire volume of the shallow cavity and a peripheral region of the deep cavity; 
 depositing a first metallic fill material in a remaining volume of the deep cavity; and 
 removing portions of the first metallic fill material and the first metallic barrier liner layer from above the second horizontal plane, wherein a first metal interconnect structure including a first metallic barrier liner and a first metallic fill material portion is formed in the stepped cavity, the first metallic barrier liner including a first remaining portion of the first metallic barrier liner layer and the first metallic fill material portion including a second remaining portion of the first metallic fill material. 
 
     
     
       2. The method of  claim 1 , wherein:
 removal of the portions of the first metallic fill material and the first metallic barrier liner layer from above the second horizontal plane is performed using a chemical mechanical polishing process; and 
 the first metallic barrier liner comprises a planar bottom barrier liner segment underlying the first metallic fill material portion and having a bottom surface located at, or below, the first horizontal plane, sidewall segments adjoined to a periphery of the planar bottom barrier liner segment and vertically extending to the second horizontal plane, and a planar top barrier liner segment adjoined to an outer sidewall of one of the sidewall segments, having a top surface located within the second horizontal plane, and laterally extending by a greater lateral distance than a lateral thickness of each of the sidewall segments. 
 
     
     
       3. The method of  claim 2 , wherein:
 the first metallic barrier liner layer comprises a conductive metallic compound material, at least one refractory metal, or a stack there of; and 
 the first metallic fill material has a different material composition than the first metallic barrier liner layer, and comprises a material selected from aluminum, an aluminum-containing alloy including aluminum at a weight percentage greater than 90%, copper, a copper-containing alloy including copper at a weight percentage greater than 50%, tungsten, molybdenum, ruthenium, cobalt, nickel, silver, gold, and intermetallic alloys thereof. 
 
     
     
       4. The method of  claim 2 , further comprising:
 forming an overlying dielectric material layer on the top surface of the interconnect-level dielectric material layer; 
 forming an additional cavity through the overlying dielectric material layer; and 
 forming a second metal interconnect structure in the additional cavity in the overlying dielectric material layer on a top surface of the first metal interconnect structure. 
 
     
     
       5. The method of  claim 4 , wherein the second metal interconnect structure contacts a top surface of the planar top barrier liner segment of the first metal interconnect structure, and does not contact the first metallic fill material portion; and
 an entirety of a top surface of the first metallic fill material portion is in contact with a bottom surface of the overlying dielectric material layer. 
 
     
     
       6. The method of  claim 1 , wherein forming the first metal interconnect structure further comprises forming the first metallic fill material portion to comprise an indented rectangular shape comprising an indented portion and a remainder portion, wherein the indented portion comprises a width that is less than a width of the remainder portion, and wherein the indented portion is located adjacent to an indentation area that is adjoined to a side of the indented rectangular shape. 
     
     
       7. A method of forming a device structure, comprising:
 forming a stepped cavity in an interconnect-level dielectric material layer such that the stepped cavity comprises a deep cavity portion and a shallow cavity portion such that the shallow cavity portion is adjacent to the deep cavity portion in a lateral direction; 
 depositing a first metallic barrier liner layer in the stepped cavity such that the first metallic barrier liner layer fills a first volume of the shallow cavity portion and covers sidewalls of the deep cavity portion; and 
 depositing a first metallic fill material in a second volume of the deep cavity portion, 
 wherein the first metallic barrier liner layer comprises a planar top barrier liner segment formed in the shallow cavity portion and adjoined to an outer sidewall of the deep cavity portion such that the planar top barrier liner segment extends laterally relative to the first metallic fill material. 
 
     
     
       8. The method of  claim 7 , wherein forming the stepped cavity in the interconnect-level dielectric material layer further comprises:
 forming the deep cavity portion to extend from a first horizontal plane including a bottom surface of the interconnect-level dielectric material layer to a second horizontal plane including a top surface of the interconnect-level dielectric material layer; and 
 forming the shallow cavity portion to extend from a third horizontal plane, located between the first horizontal plane and the second horizontal plane, to the second horizontal plane. 
 
     
     
       9. The method of  claim 8 , further comprising:
 removing portions of the first metallic fill material and the first metallic barrier liner layer from above the second horizontal plane, wherein a first metal interconnect structure including a first metallic barrier liner and a first metallic fill material portion is formed in the stepped cavity, the first metallic barrier liner including a first remaining portion of the first metallic barrier liner layer and the first metallic fill material portion including a second remaining portion of the first metallic fill material. 
 
     
     
       10. The method of  claim 9 , wherein depositing the first metallic barrier liner layer in the stepped cavity further comprises:
 forming the first metallic barrier liner to comprise a bottom surface located at, or below, the first horizontal plane and sidewall segments adjoined to a periphery of a planar bottom barrier liner segment and vertically extending to the second horizontal plane; and 
 forming the planar top barrier liner segment to be adjoined to the outer sidewall of the deep cavity portion such that the outer sidewall is one of the sidewall segments. 
 
     
     
       11. The method of  claim 10 , further comprising:
 forming the planar top barrier liner segment to have a top surface located within the second horizontal plane, and laterally extending by a greater lateral distance than a lateral thickness of each of the sidewall segments. 
 
     
     
       12. The method of  claim 9 , further comprising:
 forming an overlying dielectric material layer on a top surface of the interconnect-level dielectric material layer and over the planar top barrier liner segment and the first metallic fill material such that an entirety of a top surface of the first metallic fill material portion is in contact with a bottom surface of the overlying dielectric material layer. 
 
     
     
       13. The method of  claim 12 , further comprising:
 forming an additional cavity through the overlying dielectric material layer; and 
 forming a second metal interconnect structure in the additional cavity in the overlying dielectric material layer on a top surface of the first metal interconnect structure. 
 
     
     
       14. The method of  claim 12 , further comprising:
 forming a second metal interconnect structure such that the second metal interconnect structure contacts a top surface of the planar top barrier liner segment of the first metal interconnect structure, and does not contact the first metallic fill material portion. 
 
     
     
       15. A method of forming a device structure, comprising:
 forming an interconnect-level dielectric material layer over a substrate; and 
 forming a first stepped metal interconnect structure embedded in the interconnect-level dielectric material layer and comprising a first metallic barrier liner and a first metallic fill material portion, 
 wherein forming the first stepped metal interconnect structure further comprises forming the first metallic fill material portion to comprise an indented rectangular shape comprising an indented portion and a remainder portion, wherein the indented portion comprises a width that is less than a width of the remainder portion, and wherein the indented portion is located adjacent to an indentation area that is adjoined to a side of the indented rectangular shape. 
 
     
     
       16. The method of  claim 15 , further comprising:
 forming an overlying dielectric material layer that contacts a top surface of the interconnect-level dielectric material layer; and 
 forming a second metal interconnect structure embedded in the overlying dielectric material layer and contacting a top surface of the first stepped metal interconnect structure, 
 wherein forming the second metal interconnect structure further comprises contacting the second metal interconnect structure with a top surface of a planar top barrier liner segment of the first stepped metal interconnect structure and so that the second metal interconnect structure does not contact the first metallic fill material portion. 
 
     
     
       17. The method of  claim 16 , wherein forming the overlying dielectric material layer further comprises forming the overlying dielectric material layer such that a top surface of the first metallic fill material portion is in contact with a bottom surface of the overlying dielectric material layer. 
     
     
       18. The method of  claim 16 , wherein forming the second metal interconnect structure further comprises forming the second metal interconnect structure such that an entirety of a bottom surface of the second metal interconnect structure is located within the indentation area. 
     
     
       19. The method of  claim 16 , wherein forming the second metal interconnect structure further comprises:
 forming a first portion of a bottom surface of the second metal interconnect structure to be located within the indentation area; and 
 forming a second portion of the bottom surface of the second metal interconnect structure to be located outside a first area of the indented rectangular shape and within a second area that is adjacent to the indentation area. 
 
     
     
       20. The method of  claim 15 , wherein forming the first stepped metal interconnect structure further comprises:
 forming the first metallic barrier liner to comprise a conductive metallic compound material, at least one refractory metal, or a stack there of; and 
 forming the first metallic fill material portion to have a different material composition than the first metallic barrier liner, and to comprise a material selected from aluminum, an aluminum-containing alloy including aluminum at a weight percentage greater than 90%, copper, a copper-containing alloy including copper at a weight percentage greater than 50%, tungsten, molybdenum, ruthenium, cobalt, nickel, silver, gold, and intermetallic alloys thereof.